1. Field of the Invention
This invention relates to shingle-like metal sheets used for roofing and more particularly to an improved roofing system that allows speedy installation of metal, particularly copper that has been pre-formed into shingle-like sheets.
2. Description of the Prior Art
Due to its attributes, copper lends itself particularly well to use as a roofing material. Copper is extremely durable, being corrosion resistant and immune to most environmental forces as well as industrial based pollutants including acid rain. Copper roofing is so durable, that it may outlast the building upon which it is installed. Copper roofs are also essentially maintenance free; they do not need periodic cleaning, painting, sealing or the like. Dents and scratches ordinarily do not affect the life of copper; their effect on its appearance is generally temporary, because over time they tend to disappear as the copper ages from its original bright shine, through brown or bronze tones, and ultimately to its renowned green patina.
Copper is also noncombustible and light weight, weighing about half as much as composition shingles, one fourth as much as most tiles, and one eighth as much as quality slate.
Sheet metal copper roofing has been known and used for centuries, but was made costly by the difficulties of its installation. It is therefore desirable to provide a copper roofing system which can be installed rapidly and easily, thereby substantially reducing the cost of copper roofing, making it practicable for use in homes, small commercial buildings, and the like. The shingle-like metal sheets used in this type of system, whether fabricated of copper or of other practicable metals, will be hereinafter termed metal shingles.
The majority of prior art metal roofing systems have involved the use of long roofing panels which overlapped both vertically and horizontally in order to ensure that water was not able to reach the underlying structure. Usually these panels were designed so that successive runs of panels interlocked. Prior art patents that involve this type of construction include U.S. Pat. No. 5,146,727 to Hansson and U.S. Pat. No. 4,010,590 to Reinke. U.S. Pat. No. 4,218,857 to Vallee was for a roofing system involving a more complicated herringbone pattern laid above a base of pentagonal shingles.
In U.S. Pat. No. 3,411,259 to Anderson et al, assigned to a common assignee, there was taught a metal roofing system in which adjacent long panels abutted on their short, vertical edges rather than overlapping. Thus the long panels only overlapped in horizontal layers. A specially designed metal flashing pan (or joint pan) located underneath the abutting edges, protected the substructure from water and the like by collecting liquid and delivering it to the upper surface of the metal shingles of the horizontal row of shingles disposed directly therebelow. The teachings of the U.S. Pat. No. 3,411,259 patent to Anderson et al. are herein incorporated by reference as these teaching relate to a sheet metal roofing system wherein long courses of panels overlap in horizontal layers and abut vertically and wherein a joint plate is disposed beneath the abutting edges.
One advantage of the invention of Anderson et al. was that it provided the freedom to lay metal shingles over a previous row without having to start the process from a given position, as had to be done when overlapping vertically. This meant that an installer need not walk back to the beginning of each row, but could begin installation from where the prior row was completed. This saved time as well as limiting exposure to the problems caused by walking repeatedly across a partially completed roof. Another advantage is that this construction is resistant to high wind and other external forces of the kind that caused prior art metal shingle roofing to develop leaks.
It was desired, however, to improve upon this system by providing additional features. First, although the system could be installed more expeditiously than metal shingle roofs of the prior art, the positioning of successive rows of shingles required that the shingle installer snap chalk lines, measure and mark each shingle, or resort to other labor intensive techniques in order to attain proper alignment of the joints between shingles, the alignment and spacing of adjacent shingles, the alignment of singles with respect to those in the previous horizontal row, and the lap of shingles over the joint pan. The system of the instant invention obviates this problem by a combination of a deformation or ridge on the top of each joint pan and indicators along the upper securement border of the shingles. Proper placement and alignment of the shingles allows for maximal weatherproofing and allows room for naturally occurring expansion and contraction movement.
Second, in the earlier invention the installer received no guidance as to the proper spacing of fasteners in order to achieve maximum resistance to wind blow-off. Nor was there allowance for free expansion and contraction of the individual shingles such as might occur due to extremes in weather. Restriction at the fastener could, during shingle expansion, result in buckling or oil canning of the shingles.
In addition, the earlier invention did not use, as a part of the system, barbed copper nails as does the instant invention. The installer, left to his or her own devices, might use galvanically incompatible fasteners which could rust out or fasteners which did not possess sufficient resistance to withdrawal.